drm/omap: move out of staging

Now that the omapdss interface has been reworked so that omapdrm can use
dispc directly, we have been able to fix the remaining functional kms
issues with omapdrm.  And in the mean time the PM sequencing and many
other of that open issues have been solved.  So I think it makes sense
to finally move omapdrm out of staging.

Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/omapdrm/TODO

@@ -0,0 +1,23 @@
+TODO
+. Where should we do eviction (detatch_pages())?  We aren't necessarily
+  accessing the pages via a GART, so maybe we need some other threshold
+  to put a cap on the # of pages that can be pin'd.
+  . Use mm_shrinker to trigger unpinning pages.
+  . This is mainly theoretical since most of these devices don't actually
+    have swap or harddrive.
+. GEM/shmem backed pages can have existing mappings (kernel linear map,
+  etc..), which isn't really ideal.
+. Revisit GEM sync object infrastructure.. TTM has some framework for this
+  already.  Possibly this could be refactored out and made more common?
+  There should be some way to do this with less wheel-reinvention.
+  . This can be handled by the dma-buf fence/reservation stuff when it
+    lands
+
+Userspace:
+. git://anongit.freedesktop.org/xorg/driver/xf86-video-omap
+
+Currently tested on
+. OMAP3530 beagleboard
+. OMAP4430 pandaboard
+. OMAP4460 pandaboard
+. OMAP5432 uEVM